Li-modified nanoporous carbons for high-performance adsorption and separation of CO2 over N-2: A combined DFT and GCMC computational study

摘要

We reported the construction and analysis of nanoporous carbons (NPCs) modified with 1, 2, 4 physical and 2, 4, 6 chemical Li dopants by using density functional theory and grand canonical Monte Carlo simulations. We found that Li-modified NPCs created conducive environments for CO2 adsorption and separation over N-2, and chemical doping was superior to physical doping at the same doping number of Li. By calculating, we found that adsorption capacity and separation were determined according to the synergistic effect of pore characteristics, doping method, and quantity of Li. The saturated adsorption of CO2 follows the sequence Chem_6Li Chem_4Li Chem_2Li approximate to Phys_2Li Phys_4Li Phys_1Li NPC. Among Li-modified NPCs at 298 K and dynamic equilibrium state, Chem_6Li exhibited the best CO2 adsorption capacity of similar to 35 and selectivity of similar to 200 over N-2 with CO2/N-2 ratios of 50: 50 and 15: 85. Our calculation results highlighted the potential of Li doping as an excellent candidate for improving NPCs in carbon capture and separation.